1. Department of Mathematics, Bidhan Chandra College, Asansol - 4, West Bengal 713304, India
2. Department of Mathematics, The University of Burdwan, Burdwan 713104, West Bengal, India
3. Division of Mathematics, School of Advanced Sciences, Vellore Institute of Technology, Chennai 600127, India
4. Department of Mathematics, College of Science, King Khalid University 9004 Abha, Saudi Arabia